Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$172.27	5.652%	$182.0067	$182.01	$182.00	$182.00
Purchase #2	$64.79	6.244%	$68.8355	$68.84	$68.85	$68.80
Purchase #3	$11.34	4.787%	$11.8828	$11.88	$11.90	$11.90
Purchase #4	$152.89	4.795%	$160.2211	$160.22	$160.20	$160.20
Purchase #5	$152.64	9.830%	$167.6445	$167.64	$167.65	$167.60
Purchase #6	$152.56	7.635%	$164.208	$164.21	$164.20	$164.20
Purchase #7	$92.88	7.439%	$99.7893	$99.79	$99.80	$99.80
7 purchase totals =	$799.37		$854.5879	$854.59	$854.60	$854.50